It has been recently discovered that passive motion of a joint reduces the post-trauma accumulation of fluid and subsequently reduces the recovery time. This form of therapy has received acceptance as an advantage to the patient and a cost savings in the health care field. In particular, devices are commercially available to produce movement in the hip, knee, and ankle. A limited number of devices are available to produce movement in the digits of a hand. The problems in designing such hand devices are that the movement of the fingers and thumb are very complex and the distance traveled is relatively small. Thus, it is difficult to design a machine which is not cumbersome and heavy, and which will achieve the desired motion. It is also a problem to design such a device which is not too complex and that will stand up to the rigors of continuous use.
U.S. Pat. No. 4,644,938 issued Feb. 24, 1987 to Lubbers relates to a device to cause continuous passive motion of the hand. The device operates using an elastic biasing force which tends to pull the finger into a flexed position and a counter force which is intermittently applied to overcome the biasing force and pull the fingers into an extended position.
U.S. Pat. No. 4,665,900 issued May 19, 1987 to Saringer relates to a device mounted on the palmar side of the forearm. The device uses an elongated rod to push and pull the finger in and out of flexion and extension.
U.S. Pat. No. 4,679,548, issued Jul. 19, 1987, to Pecheux, relates to a continuous passive motion device for use with a hand where portions of the apparatus move in a spiral motion which is performed by a single, motor-driven slide guide.
The present invention provides an elegant and durable mechanism to cause continuous passive motion of one or more digits and further a mechanism which approximates the spiral motion traveled at a point near the distal end of a digit to achieve complete flexion and extension.
Further objects and advantages of the invention may be presented and discussed hereinafter.